Method and apparatus for making dunnage

ABSTRACT

An apparatus for manufacturing dunnage including a plurality of rollers for pulling a web of material through the machine, a nozzle with at least one port through which gas or liquid flows, a hammer mounted on an ultrasonic frequency converter, and an anvil mounted on the machine in a position such that the web of material can pass between the hammer and anvil while allowing the hammer to strike the anvil. The ultrasonic frequency converter is connected to a power source and generates vibrations at a frequency causing the hammer to vibrate at a frequency that will melt the portion of the material that is passing between the hammer and anvil thereby creating a seam. The ultrasonic frequency converter can be mounted on an arm and cam follower to account for variations in the thickness of the web material. The apparatus may be equipped to manufacture multiple pieces of dunnage simultaneously.

FIELD OF INVENTION

The invention relates to an improved process for producing dunnage, or“air pillows.”

BACKGROUND OF THE INVENTION

Various materials are used to insulate goods from shock during shipping.Solid materials such as polystyrene “peanuts,” cups and “worms,” pelletsof foam rubber, plastics and expanded polyurethane foam are in commonuse as a shock protector. Air cushioning material, or “air pillows,” aregenerally preferred over the above types of dunnage because it islighter in weight, can be supplied and dispensed in a controlled manner,and can be manufactured on site. Air Pillows are typically manufacturedusing rolls of sheet material, which is also easier to dispose of thanthe individual pieces of plastic dunnage after the product is removed.

Air pillows are typically manufactured on site because it is inefficientto ship preformed air pillows since they take up considerably morevolume than the sheet material. Various devices have been described toproduce sealed air dunnage, or air pillows, from sheet material. U.S.Pat. Nos. 5,188,691, 5,203,761, and 4,576,669 all propose devices forproducing air filled dunnage, typically bubble wrap, from plastic sheetson an “on demand” basis.

U.S. Pat. Nos. 6,341,473, 6,889,739 and 6,948,296 each disclose aprocess for producing dunnage on site from plastic sheets where theplastic sheets are sealed after inflation using heating elements thatcontact the plastic sheets and weld them together.

However, these aforementioned processes and devices are disadvantageousin that because the heating elements must physically contact the plasticsheeting, they can become fouled. When heating elements become fouled,the dunnage producing machines must be cleaned or the heating elementsmust be replaced, resulting in down time and lost production. It is afurther disadvantage that the aforementioned processes and devices arelimited in their production speeds because of the need to allow the airpillow material to be physically melted between the heating elements toseal the air pillows. Current air pillow producing machines run atspeeds between 18-40 feet per minute.

Another feature of existing dunnage machines are the use of two rubberwheels that engage the plastic sheeting to pull it through the inflationand sealing process. However the use of rubber wheels is disadvantageousbecause when the rubber wheels get dirty, slippage in the pillowmaterial can occur.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to produce air pillows onsite in a manner that doesn't require heating elements to weld shut theair pillows.

It is a further object of the invention to produce air pillows on siteby a process whereby the welding of the air pillow material is performedusing a high frequency welder.

It is a further object of the invention to produce air pillows on siteby a process that seals the air pillows at improved operating speeds.

It is a further object of the invention to produce air pillows with animproved seal.

It is a further object of the invention to produce air pillows using amaterial with a composition specially designed to be sealed at aspecific high frequency.

To achieve these and other objects, the present invention provides amethod for producing air pillows comprising the steps of providing, inroll form, a plurality of preformed plastic bags, where each of saidbags comprise plastic sheets stacked upon one another and sealed alongits edges except for a channel passing between the layers and open onopposite ends, the bags being removably attached in sequence along twoopposed edges, inserting a tube into the open channel and blowing airthrough the tube causing each bag to inflate in sequence, and sealingthe channel of each inflated bag to create an air pillow.

Typically, a roll of bags will be provided which is segmentedlongitudinally, but a roll can also be provided which is segmented bothlongitudinally and laterally, to produce a roll with, for example, fourbags across or eight bags across. The bags can be separated from theroll individually or can be separated in groups. This is advantageous,as the air pillows which are produced can be wrapped around an object toprotect it.

In accordance with the invention, the sealing of the open channel isaccomplished using an ultrasonic energy to weld the layers of plastic toone another By using ultrasonic energy, the plastic layers can be weldedtogether without the need for heating elements to melt the plastic.Ultrasonic welding can occur at a higher rate than if the welding weredone using physically hot elements. This technology will allow operatingspeeds that are almost 100-800% higher than existing machines.

Various types and thicknesses of material can be used to make the bagsof the invention. The composition of the material must be such that thespecific frequency of the particular ultrasonic energy generator used inan embodiment is capable of welding two or more layers of materialtogether. By adjusting the frequency of the ultrasonic energy, supplierscan control the type of plastic material that can be used on theirmachines. The thickness of the material can be adjusted to provide extrastrength or lighter weight, depending on which properties are desired.

Importantly, the apparatus used to inflate and seal plastic bags is wellknown and easy to operate. Typically, an air filled sealed bag will beused for packaging a small article. In this regard, U.S. Pat. Nos.3,254,828, 3,298,156 and 3,477,196 are cited as representative patentsshowing methods and apparatus for blowing open bags on rolls.

In an additional embodiment of the invention, a metal knurled wheel isengaged with second wheel, possibly made of rubber, such that theplastic sheet material is pulled through the dunnage machine and theinflation and welding process. The welded seal can optionally be rundirectly between the knurled and second wheel to enable the knurledpattern to be embossed in the welded seal, thereby strengthening it.

In yet an additional embodiment, the high frequency generator is mountedon an arm connected to a spring loaded cam follower, which can beadjusted based on the frequency of the generator and the speed of thematerial passing through the dunnage machine to result in a satisfactoryweld. The adjustment of the cam follower can ideally be made using a setscrew to compress or relieve the spring.

These and other objects, advantages and features of the invention willbecome apparent to those skilled in the art upon consideration of thefollowing description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a process flow for forming inflated dunnage;

FIG. 2 is a plan view of device for forming inflated dunnage;

FIG. 3 is a plan view of a portion of the dunnage inflating machine;

FIGS. 4 a and 4 b are views of the ultrasonic converter mount;

FIG. 5 is a detail view of a pulley wheel; and

FIG. 6 is a view of a device for producing higher volumes of dunnage.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail specific embodiments, with the understanding that the presentdisclosure is to be considered as an example of the principles of theinvention and not intended to limit the invention to the specificembodiments shown and described. While the following descriptiondescribes a dunnage formation system, it should be recognized theembodiments disclosed can be utilized to manufacture pouches filled withany aqueous or gaseous material. In the description below, likereference numerals are used to describe the same, similar orcorresponding parts in the several views of the drawing.

Referring now to the drawings and FIGS. 1 and 2 in particular, theprocess flow of a dunnage formation machine is shown. A web of plasticmaterial 15 such as polypropylene is provided on a spool 10. The web issegmented longitudinally as shown in FIG. 2. The machine includes anultrasonic frequency converter 18 on which a hammer unit 14 is mounted.The hammer unit 14 is arranged so that the web 15 is in contact withboth the hammer unit 14 and a rotatable anvil wheel 13. The hammer unit14 and the anvil wheel 13 are mounted such that the axis of rotation ofthe anvil wheel 13 is aligned with the central axis of the hammer unit14. Air nozzle 11 is mounted on the machine to inflate the dunnage 19 asthe web 15 passes through the machine.

When the machine is in use, pulley wheels 16 and 17 rotate to pull theweb 15 from the spool of plastic material 10. The web 15 passes over aguide roll 12 and thence to the air nozzle 11 where the air nozzle 11 ispositioned to be inserted into a portion 21 of the web 15 that is notcompletely sealed on the longitudinal edges of the non-inflated dunnage19. The air nozzle allows compressed air to blow in between the layersof the web 15, thereby inflating a segmented portion of the web 15. Thenow inflated web 15 is fed through the interface of the hammer 14 andthe anvil wheel 13 whereby layers of the web 15 are compressed andwelded shut by the energy that is created by the vibrations generated inthe hammer 14 by ultrasonic frequency converter 18. The composition ofthe plastic material of the web is such that it will liquefy whenexposed to the frequency created by the ultrasonic frequency converter18 and consequently, the layers of the plastic material of the web willbe welded together to create a seam 25 in the now inflated web 15. Oncethe web 15 has been sealed, it is cut off of the air nozzle 11 bytrimming the web material that is not part of the inflated portion ofthe web 15 or the seam 25. The seam 25 of the now inflated web 15 thenpasses through the pulley wheels 16 and 17. Either one or both of pulleywheels 16 and 17 are driven by a motor so that the web 15 is pulledthrough the machine. Inflated dunnage 19 is now the resulting product.

In practice the machine 10 will be housed within a cabinet which is notshown for clarity of illustration. The cabinet includes access doorswith an electrical interlock. When the doors are open the machine may bejogged for set up, but the machine will not operate to produce dunnageunits unless the doors are closed and latched.

In another embodiment, one or both of pulley wheels 16 and 17 areknurled wheels. In this manner, when the freshly created seam 25 passesthrough the interface between pulley wheels 16 and 17 pattern reflectiveof the knurled pattern is embossed on the still soft seam, therebystrengthening the seam.

Referring to FIG. 3, the relationship of the components of the dunnageproducing machine is described. The hammer 14 is disposed on theultrasonic frequency converter 18. An example of an ultrasonic frequencyconverter is the CRV233 Converter made by Sonics & Materials, Inc.,although it will be recognized that other ultrasonic frequencygenerators can be used. The alignment of the axis of the hammer 14 andthe anvil wheel 13 is shown. Air nozzle 11 is shown with 4 ports 31 fordistributing air into the web material, however, it will be recognizedthat many other arrangements may be used for passing the substance thatwill be used to inflate the web such as one port or more in a variety ofshapes. As shown in FIG. 3, the air nozzle is roughly in the same planeas the interface between the hammer 14 and anvil wheel 13 and betweenpulley wheels 16 and 17.

Referring now to FIGS. 4 a and 4 b the arrangement of the ultrasonicfrequency converter 14 on an adjustable arm 41 is shown. The quality ofthe welded seam 25 is highly dependent on how well the hammer 14 and theanvil wheel 13 interface with the plastic material of the web 15. Sincethe thickness of the plastic material of web 15 can differ based on theparticular material used or even within the same spool of material, aquality seam can be assured if the ultrasonic frequency converter 18 andhammer 14 assembly are mounted on an adjustable arm 41. The embodimentshown has the adjustable arm 41 riding on a spring loaded cam follower42. The tension of the spring loaded cam follower can be adjusted inthis embodiment using set screw 43, which either releases or compressesthe spring 44 in the spring loaded cam follower 42 thereby adjusting thegap between the hammer 14 and the anvil wheel 13.

Referring now to FIG. 5, an embodiment of a pulley wheel 51 is shownhaving a knurled pattern 52. In the embodiment shown, knurled pattern 52is a series of longitudinal grooves cut into the face of wheel. In oneembodiment, pulley wheel 16 is made of rubber, and pulley wheel 17 isreplaced by pulley wheel 51, which is made of metal and has knurledpattern 52 on its face. Pulley wheels 16 and 51 would be engaged in aninterfering manner such that when one or both is driven it will pull web15 through the interfering engagement and emboss the seam 25 withknurled pattern 52. In this manner, seam 25 will be made stronger, thanif no knurled pattern was present on a pulley wheels.

Referring now to FIG. 6 an embodiment is shown where multiple pieces ofinflated dunnage can be manufactured at the same time. In thisembodiment, a spool of material 61 can be provided which is segmentedboth longitudinally and laterally, to produce a roll with, for example,two bags across. As shown in this embodiment, duplicative assemblies ofair nozzles 67, ultrasonic frequency converters 68, hammers 69 and anvilwheels 70 are required such that the number of assemblies is equal tothe number of inflated dunnage that are arranged laterally on the spoolof material 61. For example, if it is desired to produce two inflateddunnage bags at the same time, a spool of material that is segmentedwith two bags laterally to each other will be run through a device thathas two assemblies with two air nozzles 67, two ultrasonic frequencyconverters 68, two hammers 69 and two anvil wheels 70. Alternatively,there could be an arrangement where there is a common seam between twolongitudinally arranged bags, such that only one ultrasonic frequencyconverter/hammer assembly would be required. Yet another embodimentcould have a single ultrasonic frequency converter unit driving twohammers.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction, operation andthe combination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

Thus it is apparent that in accordance with the present invention, anapparatus that fully satisfies the objectives, aims and advantages isset forth above. While the invention has been described in conjunctionwith specific embodiments, it is evident that many alternatives,modifications, permutations and variations will become apparent to thoseskilled in the art in light of the foregoing description. Accordingly,it is intended that the present invention embrace all such alternatives,modifications and variations as fall within the scope of the appendedclaims.

1. An apparatus for manufacturing dunnage comprising: a plurality ofrollers for pulling a web of material through the machine; a nozzle withat least one port through which gas or liquid flows; a hammer mounted onan ultrasonic frequency converter; an anvil mounted on the machine in aposition such that the web of material can pass between the hammer andanvil while allowing the hammer to strike the anvil; the ultrasonicfrequency converter being connected to a power source and generatingvibrations at a frequency causing the hammer to vibrate at a frequencythat will melt the portion of the material that is passing between thehammer and anvil thereby creating a seam.
 2. An apparatus formanufacturing dunnage comprising: means for pulling a web of material ofa plurality of layers including predefined sections through the machine;means for inflating the predefined sections of the web of material andforming a pouch; ultrasonic frequency means for welding the layers of aportion of the inflated web of material.
 3. A method for making dunnage,comprising: providing a web of material with a plurality of layers andpredefined lateral and transverse edges forming pouches; passing thematerial over a nozzle, so that the nozzle is positioned between atleast two of the layers; inflating the pouches with a gaseous or liquidmaterial flowing through the nozzle; passing the material between ananvil and hammer, the hammer being mounted on an ultrasonic frequencygenerator; the ultrasonic frequency converter generating vibrations at afrequency such that when the material passes between the anvil andhammer, the material melts creating a seam and the pouches are sealed,thereby creating sealed dunnage pouches.